Fuel injection system for an internal combustion engine

The fuel injection system (10), for an internal combustion motor, has an injection pump (14) and a tank (20) to hold the fuel which is at a medium pressure level with a vapor pressure higher than atmospheric pressure, as liquefied petroleum gas (LPG). The pressure in the tank is at a higher level than the fuel vapor pressure. A fuel pump (24) within the tank feeds the fuel to the injection pump. A second fuel pump (30) is in the fuel line (22) to the injection pump, outside the tank and downstream of the first fuel pump, to increase the fuel pressure.